1. Field of the Invention
This invention relates generally to security systems and devices for use with containers having some metallic portion to hold a security tag, e.g., an EAS tag, an RFID tag, etc., and more particularly, to devices for holding such a tag on the container such that an RF receiver is able to readily discern a return signal from the tag, to systems making use of such devices, and to methods of using such systems and calibrating such tags.
2. Description of Related Art
The prior art teaches various mechanisms of using security tags to secure a multitude of different products. Some examples of commonly known security tags are RF, AM and UHF tag, traditionally known as electronic article surveillance (EAS) tags. Other security tags, e.g., radio frequency identification (RFID) tags, make use of electronic chips. EAS, RFID and other types of electronic security tags can be and are used mounted or secured to many different products, e.g., books, pallets, containers, and electronics. Heretofore, products that are housed in containers or cans having metallic portions, e.g., containers or cans for baby foods and other foodstuffs, etc., have not been effectively tagged.
As will be appreciated by those skilled in the art, many containers for foods are made of plastic. However, plastic has inherent limitations for housing such products. For example, plastic may allow trace amounts of bacteria through it. Baby food manufacturers are particularly sensitive to the limitations of plastics as a container medium and consequentially, many such manufacturers make their containers or cans out of cardboard tubular midsection having a pressed, thin aluminum foil around the outside of the midsection as a means for preventing liquid leakage out of the container. Additionally, the lid and the base of the can or container are generally made of a thin aluminum sheet. A relatively thick, annular aluminum annular ring serves to join the lid to the cardboard midsection, a similar ring serves to join the base to the cardboard midsection. This arrangement provides an inexpensive, easily manufactured, waterproof container that can safely hold foodstuffs. However, such containers include so much metal that they cannot be effectively tagged with an EAS, RFID or other electromagnetic radiation based tag, since the metal of the container will interfere with the electromagnetic properties of the tag, e.g., the metal portion of the can will reduce the amplitude of the return signal from the tag. Moreover, the metallic portion of the container also tends acts as an antenna, thereby altering the frequency response of the tag.
Thus, a need exists for a device which will enable the effective tagging of containers that include substantial metallic portions, e.g., baby food containers, soup containers, etc.